Embodiments described herein relate to an image transfer product such as a printing blanket, printing sleeve, or printing belt, and more particularly, to an image transfer product including a phase change material in one or more layers of the product to regulate the temperature of the product during printing operations.
Image transfer products such as printing blankets, printing sleeves, printing rollers, belts, and the like are used in a number of printing processes, including sheet and web offset lithography, electrophotographic printing, and hybrids of electrophotographic or inkjet printing combined with transfuse printing. The function of the image transfer products is to repeatedly and consistently transfer an image of ink, or solid or liquid toner, onto a substrate such as paper, plastic film, or the like.
Such image transfer products are subjected to various environmental and operational conditions which can affect the temperature of the ink or toner transfer surface. Operation at temperatures which are greater than or less than optimal may adversely affect print quality, ink performance, and image transfer product performance. For example, temperature variations in the print surface of an image transfer product can cause problems with transfer consistency, and consequently, reduce the quality of the image transferred to the substrate. Such temperature variations can be caused by a number of factors including ink or paper piling, the ambient temperature of the image transfer system, substrate variation, printing speed, ink variation, fountain solution variation, nip pressure, printing plate aging, and aging of the image transfer product. Conversely, temperature variations can cause conditions such as ink piling, substrate release, or lack of lubricity, leading to poor performance of the printing system.
In addition to temperature variations, feed variation at transfer nips is also a problem for some image transfer products. By “feed variation,” it is meant the relative difference in the actual speed of the substrate versus the press design speed through a transfer nip. A positive feed variation passes the substrate more quickly than the substrate design speed of a particular press, while a negative feed variation passes the substrate more slowly than the substrate design speed of a press.
Various physical properties of the image transfer product can also affect feed behavior. When the feed behavior of the image transfer product is affected by temperature fluctuations, print quality and substrate handling may be adversely affected, resulting in improper web tension, sheet curl, color registration, and uneven print length.
Accordingly, there is a need in the art for an improved image transfer product which is adapted to dampen temperature fluctuations that can occur during printing to improve the consistency and quality of the image transferred to a substrate.